1. Field of the Invention
This invention relates to adjusting devices forming a part of telescopically adjustable top rails of window sashes, panel sashes, doors or other building components.
2. Prior Art
By "adjusting device" is meant a device for adjusting the height of the window sash or the like to be complemental to that of the opening in its window frame. In order to facilitate the installation of the window sashes, panel sash or the like into their respective window frames, it is desirable that the height of the sashes be slightly adjustable after being mounted within the respective window frames. The sash may first be mounted into its window frame with the top rail of the sash in its lowered state. After the mounting of the sash into its frame, the top rail is elevated to mate with the header of the window frame to provide effective and smooth opening and closing operation of the sash and to avoid the occurence of any accidental misfit between the sash and the window frame. For this purpose, an adjustable top rail has been proposed previously.
The prior adjustable top rail generally has two L-shaped corner key blocks made of solid plastic, wood or other suitable material, each key block being securely attached at both ends of the top rail. The L-shaped corner key block has a downwardly extending leg which is frictionally received into a channel provided in a vertical stile of the sash to assist in securing the stile and the top rail together as well as to permit the top rail to telescopically elevate in a vertical direction. In order to adjust and maintain the top rail in its desired height, an adjusting device for regulating the height is needed.
A prior art adjusting device for use with such an adjustable top rail generally comprises a substantially flat right angular member having two legs and an adjusting screw provided on one of its legs. The adjusting device of this configuration is secured onto a panel member of the sash in the vicinity of an upper corner defined by the top rail and one of the stiles of the sash in an inverted L-shaped fashion when seen from the transverse direction so that the leg bearing the adjusting screw lies horizontally and immediately beneath the top rail of the sash. The adjusting device of this configuration has imposed a limitation upon the projecting length of the adjusting screw which projects upwardly from the leg. As the leg and the top rail are so closely positioned with respect to each other, the projecting length of the adjusting screw is rendered extremely short, i.e. the adjusting screw is held by the leg only at its endmost portion. The adjusting screw is therefore prone to be easily detached from its screw hole provided on the leg when loosened slightly as a result of vibration or shock such as caused by the opening and closing of the sash. The adjusting device of such configuration furthermore has a drawback in that a screw driver or any other similar tool for attaching the device onto the panel or sash, frequently abuts against the adjusting screw during the installation of a mounting screw. In order to avoid this, the assembler or the worker must first detach the adjusting screw from the horizontally projecting leg before the device can be attached onto the panel member with a mounting screw or any other fastening means. This operation is time consuming and tedious on the part of the assembler, especially where there is a little space.